This would be an issue you’d need to approach Apple on, I suspect. Sonos isn’t terminating the connection while idle, Apple is. 

Thank you for that information! I was wondering where I am right with this.

I talked to Apple today about this and they seem to know this problem. They said something like when you stream video it goes over a 5ghz connection and music goes over 2,4 ghz. They said the Sonos would change its frequency in idle mode and doesn’t find back when audio is played from the Apple TV.

seems like Sonos could maybe fix this issue.

Sounds like mumbo-jumbo from Apple to me. What has video to do with Sonos?

Your speakers are not really connected in to your ATV by Airplay. Airplay from your ATV is just one possible source for playing to Sonos speakers.

I see. I don’t know exactly what they meant. Something about the Sonos switching frequency when it goes to idle mode. And they said the only solution is to reconnect so reestablish the airplay connection. And that’s not really a suitable solution I think. I don’t really know where I am right with this but I thought maybe somebody from Sonos  maybe could say something to this. It still seems like a bug to me. When I connect my iPhone via Airplay to the Sonos everything works fine so why not from the Apple TV.

i just wanna listen to music from my Apple TV via airplay on my Sonos without problems 

It sounds to like Apple Support Staff may have perhaps ‘fobbed’ you off - if everything works okay when using Airplay with their iPhone, (as you mention), then I would ask them why their Apple TV Airplay does not work in the same way as the phone?

It sounds like it’s their device that’s doing something different in this instance, and that’s based on your own experience of using each of their products.

So I now testet it again with my phone and now recognized that there is also this problem. I just didn’t notice so far because I usually connect my phone and instantly play music. When I stop the music and play it again after a while I have a pretty long delay until the music starts again. So it seems like it’s not a problem of the device but Airplay in general. I will inform Apple about this issue for sure. I saw another topic in this community now that more people are having this problem. I don’t wanna blame anyone, I still can’t figure if it’s a Sonos software problem with their Airplay 2 implementation or an Apple issue with Airplay 2 in general. Maybe we’ll find out!

Well this at least makes far more sense to me, because it’s clear that Apple do try their level best to squeeze more battery life out of their mobile devices each ‘year on year’, especially the iPhone (as many users do complain about that issue), so perhaps these Airplay connections are set on their devices, across the board, to time-out after a while to save on battery life or help with energy efficiency.

Maybe you will be able to persuade Apple however to remove that restriction from the Apple TV product (or increase the time-out period), although I guess that may fly in the face of keeping their devices energy efficient and they may just think that setting up the Airplay connection to a speaker again, is not that much of a problem when a user stops using the connected speaker for a determined period of time.